Vacuum tube



Dec. 29, 1931. c. J. KAYKO l, 838,488

VACUUM TUBE Filed May 21, 1928 rugged and will not go out of shape easily.

Patented Dec. 29, 1931 UNITED l 'STATES THE sPARKs-WirI-IINGTON COMPANY, or JACKSQN, MIGHrGAN, AconroRATIoNor Application led May 2K1,

more particularly to those tubes, the cathodes Y of which are heated by alternating current.

One of the objects Vof my invention is to produce a tube which is easily exhausted and does not have an excessive amount of insulating material which makes this process difficult. y

Another of the objects of my invention is to provide a type of construction which is Another of the objects of my invention is so to choose the material of which the heater is made that electrons will bevemitted from it with difficulty, thereby minimizing hum when alternating current flows through the heater.

I-Iow I accomplish these results is clearly set forth in the following specification.

Figure l -is a sectionalized view of my tube in which -lis a carbon helix secured to supporting and conducting members 6.6 by clamp paste shown at 5.5.

2 is a carbon rod covered with emitter material, such as an alkaline earth oxide or oxides also secured to a conducting and supporting member -7-g by clamp paste. The tip `of part -2- (the emitter and cathode) projects a short distance beyond the helical' A screen grid -3- horizontally disposed above the emitter is welded to a conductor and support --8- and forstiffness is also welded to a wire I3- projecting from the insulating bead V-9 melted onthe plate-support -10.

Above the grid welded to supports-40- and l1- is a plate l2-in the form of a round disk of suitable metal.

The operation of thisvery simple tube is as follows: Alternating current is fed into the heating helix -l-,. It should be noticed that this heater coil is not connected to the so-called radio-7 parts of the tube. VThe rod -2- will now be heated by radiation. Since this is the grid return (cathode) electrons will flow from this tothe plate -4-.

The varying potential gradients along the helix will not disturb the operation of the tube for the emitter is efficient. V The plate VACUUM current-can `easily :be `madefvery large, but

veryflittle current comparatively would iiow cathode to anode. Their effect, if any, is so small that no hum can be heard even in multistage amplifiers.V v

I choose carbon as a 'heating Vmaterial for the above and for the following reasons. Its electron emission is extraordinarily low, it will not sag and go out of shape as do metall filamentsand its resistance is somuch higher than metal that fairly high filament` voltages may be conveniently used. This feature is valuable both in cutting down size of the filament leadsrand making drop-wire operation from 110 volts D. C. lighting mains practical.

I choose carbon as a support for the oxide CHARLES J. xAYxo, or JACKSON, MICHIGAMLASSIGNOR, BY nnsnngAssrGnMENrs', To

emitter coating because the insulation of this Y tube depends on the maintenance of the space relationship between heating helix and emitter rod. A metal rod'has a greater tendency to warp.

vIt will thus be seen that I have produced a very simple device which makes A. C. operation of radio tubes practical. I have eliminated, too, many aggravating points in the manufacture of such tubes, such as the de-v gassing of porcelain insulators, etc. The small amount of material in the tube makes pumping a simple process.

I have illustrated the actual tubes have m electrical contact therewith, a grid electrode A positioned above said cathode, a plate electrode in spaced parallel relation to said grid electrode, and leads through said press connected to said electrodes and said heater, said 5 leads also serving as supporting means for said electrodes and said heater.

2. An electron discharge tube comprising a loullo7 a press, a carbon rod cathode supported at one end and having an electron le emitting coated portion on the other end, a helical carbon heater surrounding said cath'- ode in part but out of electrical contact therewith, a grid electrode positioned above said cathode, a plate electrode in spaced parallel relation to said grid electrode, and leads through said press connected to said electrodes and said heater, said leads also serving as supporting means for said electrodes and said heater. In Witness whereof I have hereunto set my hand this 12 day of May,l928.

CHAS. J. KAYKO. 

